The present invention relates to an air pump for an aquarium, and more particularly, to an improved air pump which is used for an ornamental aquarium and does not make noise during operation, meaning the air pump can generate bubbles without making noise.
The air pump according to the present invention has a rectifying diode and smoothing condenser connected to a power source part in order to transmit electric power to the oscillation part and the amplification part by means of converting standard electric alternating current power into direct current, and a variable resistance is connected to the oscillation part of an instable multi-vibrator circuit in order to vary the polarity of the electromagnetic coil for controlling the driving frequency from 10 Hz to 30 Hz optionally and then to widen the vibration of a vibrating lever for the purpose of minimizing noisy sounds and preventing a decrease of the quantity of air.
Two resistances and two transistors are connected within the amplification part in order to induct electric current to the electromagnetic coil for the purpose of forming bipolar fields.
In the present invention, according to the above described formation, the efficiency of air pumping can be raised, the inventive device can be formed simply and can be set into a relatively small container, and the life of the inventive device can be extremely long by virture of the simple formation and by preventing decrease of the stroke of the air pump.